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-rw-r--r--net/mptcp/options.c1633
1 files changed, 1633 insertions, 0 deletions
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
new file mode 100644
index 000000000..a718ebcb5
--- /dev/null
+++ b/net/mptcp/options.c
@@ -0,0 +1,1633 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Multipath TCP
+ *
+ * Copyright (c) 2017 - 2019, Intel Corporation.
+ */
+
+#define pr_fmt(fmt) "MPTCP: " fmt
+
+#include <linux/kernel.h>
+#include <crypto/sha2.h>
+#include <net/tcp.h>
+#include <net/mptcp.h>
+#include "protocol.h"
+#include "mib.h"
+
+#include <trace/events/mptcp.h>
+
+static bool mptcp_cap_flag_sha256(u8 flags)
+{
+ return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
+}
+
+static void mptcp_parse_option(const struct sk_buff *skb,
+ const unsigned char *ptr, int opsize,
+ struct mptcp_options_received *mp_opt)
+{
+ u8 subtype = *ptr >> 4;
+ int expected_opsize;
+ u8 version;
+ u8 flags;
+ u8 i;
+
+ switch (subtype) {
+ case MPTCPOPT_MP_CAPABLE:
+ /* strict size checking */
+ if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
+ if (skb->len > tcp_hdr(skb)->doff << 2)
+ expected_opsize = TCPOLEN_MPTCP_MPC_ACK_DATA;
+ else
+ expected_opsize = TCPOLEN_MPTCP_MPC_ACK;
+ } else {
+ if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)
+ expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK;
+ else
+ expected_opsize = TCPOLEN_MPTCP_MPC_SYN;
+ }
+
+ /* Cfr RFC 8684 Section 3.3.0:
+ * If a checksum is present but its use had
+ * not been negotiated in the MP_CAPABLE handshake, the receiver MUST
+ * close the subflow with a RST, as it is not behaving as negotiated.
+ * If a checksum is not present when its use has been negotiated, the
+ * receiver MUST close the subflow with a RST, as it is considered
+ * broken
+ * We parse even option with mismatching csum presence, so that
+ * later in subflow_data_ready we can trigger the reset.
+ */
+ if (opsize != expected_opsize &&
+ (expected_opsize != TCPOLEN_MPTCP_MPC_ACK_DATA ||
+ opsize != TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM))
+ break;
+
+ /* try to be gentle vs future versions on the initial syn */
+ version = *ptr++ & MPTCP_VERSION_MASK;
+ if (opsize != TCPOLEN_MPTCP_MPC_SYN) {
+ if (version != MPTCP_SUPPORTED_VERSION)
+ break;
+ } else if (version < MPTCP_SUPPORTED_VERSION) {
+ break;
+ }
+
+ flags = *ptr++;
+ if (!mptcp_cap_flag_sha256(flags) ||
+ (flags & MPTCP_CAP_EXTENSIBILITY))
+ break;
+
+ /* RFC 6824, Section 3.1:
+ * "For the Checksum Required bit (labeled "A"), if either
+ * host requires the use of checksums, checksums MUST be used.
+ * In other words, the only way for checksums not to be used
+ * is if both hosts in their SYNs set A=0."
+ */
+ if (flags & MPTCP_CAP_CHECKSUM_REQD)
+ mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD;
+
+ mp_opt->deny_join_id0 = !!(flags & MPTCP_CAP_DENY_JOIN_ID0);
+
+ mp_opt->suboptions |= OPTIONS_MPTCP_MPC;
+ if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {
+ mp_opt->sndr_key = get_unaligned_be64(ptr);
+ ptr += 8;
+ }
+ if (opsize >= TCPOLEN_MPTCP_MPC_ACK) {
+ mp_opt->rcvr_key = get_unaligned_be64(ptr);
+ ptr += 8;
+ }
+ if (opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA) {
+ /* Section 3.1.:
+ * "the data parameters in a MP_CAPABLE are semantically
+ * equivalent to those in a DSS option and can be used
+ * interchangeably."
+ */
+ mp_opt->suboptions |= OPTION_MPTCP_DSS;
+ mp_opt->use_map = 1;
+ mp_opt->mpc_map = 1;
+ mp_opt->use_ack = 0;
+ mp_opt->data_len = get_unaligned_be16(ptr);
+ ptr += 2;
+ }
+ if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM) {
+ mp_opt->csum = get_unaligned((__force __sum16 *)ptr);
+ mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD;
+ ptr += 2;
+ }
+ pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u",
+ version, flags, opsize, mp_opt->sndr_key,
+ mp_opt->rcvr_key, mp_opt->data_len, mp_opt->csum);
+ break;
+
+ case MPTCPOPT_MP_JOIN:
+ if (opsize == TCPOLEN_MPTCP_MPJ_SYN) {
+ mp_opt->suboptions |= OPTION_MPTCP_MPJ_SYN;
+ mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
+ mp_opt->join_id = *ptr++;
+ mp_opt->token = get_unaligned_be32(ptr);
+ ptr += 4;
+ mp_opt->nonce = get_unaligned_be32(ptr);
+ ptr += 4;
+ pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u",
+ mp_opt->backup, mp_opt->join_id,
+ mp_opt->token, mp_opt->nonce);
+ } else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) {
+ mp_opt->suboptions |= OPTION_MPTCP_MPJ_SYNACK;
+ mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
+ mp_opt->join_id = *ptr++;
+ mp_opt->thmac = get_unaligned_be64(ptr);
+ ptr += 8;
+ mp_opt->nonce = get_unaligned_be32(ptr);
+ ptr += 4;
+ pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u",
+ mp_opt->backup, mp_opt->join_id,
+ mp_opt->thmac, mp_opt->nonce);
+ } else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) {
+ mp_opt->suboptions |= OPTION_MPTCP_MPJ_ACK;
+ ptr += 2;
+ memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN);
+ pr_debug("MP_JOIN hmac");
+ }
+ break;
+
+ case MPTCPOPT_DSS:
+ pr_debug("DSS");
+ ptr++;
+
+ /* we must clear 'mpc_map' be able to detect MP_CAPABLE
+ * map vs DSS map in mptcp_incoming_options(), and reconstruct
+ * map info accordingly
+ */
+ mp_opt->mpc_map = 0;
+ flags = (*ptr++) & MPTCP_DSS_FLAG_MASK;
+ mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0;
+ mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0;
+ mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0;
+ mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0;
+ mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK);
+
+ pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d",
+ mp_opt->data_fin, mp_opt->dsn64,
+ mp_opt->use_map, mp_opt->ack64,
+ mp_opt->use_ack);
+
+ expected_opsize = TCPOLEN_MPTCP_DSS_BASE;
+
+ if (mp_opt->use_ack) {
+ if (mp_opt->ack64)
+ expected_opsize += TCPOLEN_MPTCP_DSS_ACK64;
+ else
+ expected_opsize += TCPOLEN_MPTCP_DSS_ACK32;
+ }
+
+ if (mp_opt->use_map) {
+ if (mp_opt->dsn64)
+ expected_opsize += TCPOLEN_MPTCP_DSS_MAP64;
+ else
+ expected_opsize += TCPOLEN_MPTCP_DSS_MAP32;
+ }
+
+ /* Always parse any csum presence combination, we will enforce
+ * RFC 8684 Section 3.3.0 checks later in subflow_data_ready
+ */
+ if (opsize != expected_opsize &&
+ opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM)
+ break;
+
+ mp_opt->suboptions |= OPTION_MPTCP_DSS;
+ if (mp_opt->use_ack) {
+ if (mp_opt->ack64) {
+ mp_opt->data_ack = get_unaligned_be64(ptr);
+ ptr += 8;
+ } else {
+ mp_opt->data_ack = get_unaligned_be32(ptr);
+ ptr += 4;
+ }
+
+ pr_debug("data_ack=%llu", mp_opt->data_ack);
+ }
+
+ if (mp_opt->use_map) {
+ if (mp_opt->dsn64) {
+ mp_opt->data_seq = get_unaligned_be64(ptr);
+ ptr += 8;
+ } else {
+ mp_opt->data_seq = get_unaligned_be32(ptr);
+ ptr += 4;
+ }
+
+ mp_opt->subflow_seq = get_unaligned_be32(ptr);
+ ptr += 4;
+
+ mp_opt->data_len = get_unaligned_be16(ptr);
+ ptr += 2;
+
+ if (opsize == expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) {
+ mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD;
+ mp_opt->csum = get_unaligned((__force __sum16 *)ptr);
+ ptr += 2;
+ }
+
+ pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
+ mp_opt->data_seq, mp_opt->subflow_seq,
+ mp_opt->data_len, !!(mp_opt->suboptions & OPTION_MPTCP_CSUMREQD),
+ mp_opt->csum);
+ }
+
+ break;
+
+ case MPTCPOPT_ADD_ADDR:
+ mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO;
+ if (!mp_opt->echo) {
+ if (opsize == TCPOLEN_MPTCP_ADD_ADDR ||
+ opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT)
+ mp_opt->addr.family = AF_INET;
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+ else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 ||
+ opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT)
+ mp_opt->addr.family = AF_INET6;
+#endif
+ else
+ break;
+ } else {
+ if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE ||
+ opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT)
+ mp_opt->addr.family = AF_INET;
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+ else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE ||
+ opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT)
+ mp_opt->addr.family = AF_INET6;
+#endif
+ else
+ break;
+ }
+
+ mp_opt->suboptions |= OPTION_MPTCP_ADD_ADDR;
+ mp_opt->addr.id = *ptr++;
+ mp_opt->addr.port = 0;
+ mp_opt->ahmac = 0;
+ if (mp_opt->addr.family == AF_INET) {
+ memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4);
+ ptr += 4;
+ if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT ||
+ opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) {
+ mp_opt->addr.port = htons(get_unaligned_be16(ptr));
+ ptr += 2;
+ }
+ }
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+ else {
+ memcpy(mp_opt->addr.addr6.s6_addr, (u8 *)ptr, 16);
+ ptr += 16;
+ if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT ||
+ opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) {
+ mp_opt->addr.port = htons(get_unaligned_be16(ptr));
+ ptr += 2;
+ }
+ }
+#endif
+ if (!mp_opt->echo) {
+ mp_opt->ahmac = get_unaligned_be64(ptr);
+ ptr += 8;
+ }
+ pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d",
+ (mp_opt->addr.family == AF_INET6) ? "6" : "",
+ mp_opt->addr.id, mp_opt->ahmac, mp_opt->echo, ntohs(mp_opt->addr.port));
+ break;
+
+ case MPTCPOPT_RM_ADDR:
+ if (opsize < TCPOLEN_MPTCP_RM_ADDR_BASE + 1 ||
+ opsize > TCPOLEN_MPTCP_RM_ADDR_BASE + MPTCP_RM_IDS_MAX)
+ break;
+
+ ptr++;
+
+ mp_opt->suboptions |= OPTION_MPTCP_RM_ADDR;
+ mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE;
+ for (i = 0; i < mp_opt->rm_list.nr; i++)
+ mp_opt->rm_list.ids[i] = *ptr++;
+ pr_debug("RM_ADDR: rm_list_nr=%d", mp_opt->rm_list.nr);
+ break;
+
+ case MPTCPOPT_MP_PRIO:
+ if (opsize != TCPOLEN_MPTCP_PRIO)
+ break;
+
+ mp_opt->suboptions |= OPTION_MPTCP_PRIO;
+ mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP;
+ pr_debug("MP_PRIO: prio=%d", mp_opt->backup);
+ break;
+
+ case MPTCPOPT_MP_FASTCLOSE:
+ if (opsize != TCPOLEN_MPTCP_FASTCLOSE)
+ break;
+
+ ptr += 2;
+ mp_opt->rcvr_key = get_unaligned_be64(ptr);
+ ptr += 8;
+ mp_opt->suboptions |= OPTION_MPTCP_FASTCLOSE;
+ pr_debug("MP_FASTCLOSE: recv_key=%llu", mp_opt->rcvr_key);
+ break;
+
+ case MPTCPOPT_RST:
+ if (opsize != TCPOLEN_MPTCP_RST)
+ break;
+
+ if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
+ break;
+
+ mp_opt->suboptions |= OPTION_MPTCP_RST;
+ flags = *ptr++;
+ mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT;
+ mp_opt->reset_reason = *ptr;
+ pr_debug("MP_RST: transient=%u reason=%u",
+ mp_opt->reset_transient, mp_opt->reset_reason);
+ break;
+
+ case MPTCPOPT_MP_FAIL:
+ if (opsize != TCPOLEN_MPTCP_FAIL)
+ break;
+
+ ptr += 2;
+ mp_opt->suboptions |= OPTION_MPTCP_FAIL;
+ mp_opt->fail_seq = get_unaligned_be64(ptr);
+ pr_debug("MP_FAIL: data_seq=%llu", mp_opt->fail_seq);
+ break;
+
+ default:
+ break;
+ }
+}
+
+void mptcp_get_options(const struct sk_buff *skb,
+ struct mptcp_options_received *mp_opt)
+{
+ const struct tcphdr *th = tcp_hdr(skb);
+ const unsigned char *ptr;
+ int length;
+
+ /* initialize option status */
+ mp_opt->suboptions = 0;
+
+ length = (th->doff * 4) - sizeof(struct tcphdr);
+ ptr = (const unsigned char *)(th + 1);
+
+ while (length > 0) {
+ int opcode = *ptr++;
+ int opsize;
+
+ switch (opcode) {
+ case TCPOPT_EOL:
+ return;
+ case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
+ length--;
+ continue;
+ default:
+ if (length < 2)
+ return;
+ opsize = *ptr++;
+ if (opsize < 2) /* "silly options" */
+ return;
+ if (opsize > length)
+ return; /* don't parse partial options */
+ if (opcode == TCPOPT_MPTCP)
+ mptcp_parse_option(skb, ptr, opsize, mp_opt);
+ ptr += opsize - 2;
+ length -= opsize;
+ }
+ }
+}
+
+bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
+ unsigned int *size, struct mptcp_out_options *opts)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+
+ /* we will use snd_isn to detect first pkt [re]transmission
+ * in mptcp_established_options_mp()
+ */
+ subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
+ if (subflow->request_mptcp) {
+ opts->suboptions = OPTION_MPTCP_MPC_SYN;
+ opts->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk));
+ opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk));
+ *size = TCPOLEN_MPTCP_MPC_SYN;
+ return true;
+ } else if (subflow->request_join) {
+ pr_debug("remote_token=%u, nonce=%u", subflow->remote_token,
+ subflow->local_nonce);
+ opts->suboptions = OPTION_MPTCP_MPJ_SYN;
+ opts->join_id = subflow->local_id;
+ opts->token = subflow->remote_token;
+ opts->nonce = subflow->local_nonce;
+ opts->backup = subflow->request_bkup;
+ *size = TCPOLEN_MPTCP_MPJ_SYN;
+ return true;
+ }
+ return false;
+}
+
+static void clear_3rdack_retransmission(struct sock *sk)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+
+ sk_stop_timer(sk, &icsk->icsk_delack_timer);
+ icsk->icsk_ack.timeout = 0;
+ icsk->icsk_ack.ato = 0;
+ icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
+}
+
+static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
+ bool snd_data_fin_enable,
+ unsigned int *size,
+ unsigned int remaining,
+ struct mptcp_out_options *opts)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+ struct mptcp_ext *mpext;
+ unsigned int data_len;
+ u8 len;
+
+ /* When skb is not available, we better over-estimate the emitted
+ * options len. A full DSS option (28 bytes) is longer than
+ * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
+ * tell the caller to defer the estimate to
+ * mptcp_established_options_dss(), which will reserve enough space.
+ */
+ if (!skb)
+ return false;
+
+ /* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */
+ if (subflow->fully_established || snd_data_fin_enable ||
+ subflow->snd_isn != TCP_SKB_CB(skb)->seq ||
+ sk->sk_state != TCP_ESTABLISHED)
+ return false;
+
+ if (subflow->mp_capable) {
+ mpext = mptcp_get_ext(skb);
+ data_len = mpext ? mpext->data_len : 0;
+
+ /* we will check ops->data_len in mptcp_write_options() to
+ * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
+ * TCPOLEN_MPTCP_MPC_ACK
+ */
+ opts->data_len = data_len;
+ opts->suboptions = OPTION_MPTCP_MPC_ACK;
+ opts->sndr_key = subflow->local_key;
+ opts->rcvr_key = subflow->remote_key;
+ opts->csum_reqd = READ_ONCE(msk->csum_enabled);
+ opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk));
+
+ /* Section 3.1.
+ * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
+ * packets that start the first subflow of an MPTCP connection,
+ * as well as the first packet that carries data
+ */
+ if (data_len > 0) {
+ len = TCPOLEN_MPTCP_MPC_ACK_DATA;
+ if (opts->csum_reqd) {
+ /* we need to propagate more info to csum the pseudo hdr */
+ opts->data_seq = mpext->data_seq;
+ opts->subflow_seq = mpext->subflow_seq;
+ opts->csum = mpext->csum;
+ len += TCPOLEN_MPTCP_DSS_CHECKSUM;
+ }
+ *size = ALIGN(len, 4);
+ } else {
+ *size = TCPOLEN_MPTCP_MPC_ACK;
+ }
+
+ pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
+ subflow, subflow->local_key, subflow->remote_key,
+ data_len);
+
+ return true;
+ } else if (subflow->mp_join) {
+ opts->suboptions = OPTION_MPTCP_MPJ_ACK;
+ memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN);
+ *size = TCPOLEN_MPTCP_MPJ_ACK;
+ pr_debug("subflow=%p", subflow);
+
+ /* we can use the full delegate action helper only from BH context
+ * If we are in process context - sk is flushing the backlog at
+ * socket lock release time - just set the appropriate flag, will
+ * be handled by the release callback
+ */
+ if (sock_owned_by_user(sk))
+ set_bit(MPTCP_DELEGATE_ACK, &subflow->delegated_status);
+ else
+ mptcp_subflow_delegate(subflow, MPTCP_DELEGATE_ACK);
+ return true;
+ }
+ return false;
+}
+
+static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
+ struct sk_buff *skb, struct mptcp_ext *ext)
+{
+ /* The write_seq value has already been incremented, so the actual
+ * sequence number for the DATA_FIN is one less.
+ */
+ u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1;
+
+ if (!ext->use_map || !skb->len) {
+ /* RFC6824 requires a DSS mapping with specific values
+ * if DATA_FIN is set but no data payload is mapped
+ */
+ ext->data_fin = 1;
+ ext->use_map = 1;
+ ext->dsn64 = 1;
+ ext->data_seq = data_fin_tx_seq;
+ ext->subflow_seq = 0;
+ ext->data_len = 1;
+ } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
+ /* If there's an existing DSS mapping and it is the
+ * final mapping, DATA_FIN consumes 1 additional byte of
+ * mapping space.
+ */
+ ext->data_fin = 1;
+ ext->data_len++;
+ }
+}
+
+static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
+ bool snd_data_fin_enable,
+ unsigned int *size,
+ unsigned int remaining,
+ struct mptcp_out_options *opts)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+ unsigned int dss_size = 0;
+ struct mptcp_ext *mpext;
+ unsigned int ack_size;
+ bool ret = false;
+ u64 ack_seq;
+
+ opts->csum_reqd = READ_ONCE(msk->csum_enabled);
+ mpext = skb ? mptcp_get_ext(skb) : NULL;
+
+ if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) {
+ unsigned int map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
+
+ if (mpext) {
+ if (opts->csum_reqd)
+ map_size += TCPOLEN_MPTCP_DSS_CHECKSUM;
+
+ opts->ext_copy = *mpext;
+ }
+
+ remaining -= map_size;
+ dss_size = map_size;
+ if (skb && snd_data_fin_enable)
+ mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
+ opts->suboptions = OPTION_MPTCP_DSS;
+ ret = true;
+ }
+
+ /* passive sockets msk will set the 'can_ack' after accept(), even
+ * if the first subflow may have the already the remote key handy
+ */
+ opts->ext_copy.use_ack = 0;
+ if (!READ_ONCE(msk->can_ack)) {
+ *size = ALIGN(dss_size, 4);
+ return ret;
+ }
+
+ ack_seq = READ_ONCE(msk->ack_seq);
+ if (READ_ONCE(msk->use_64bit_ack)) {
+ ack_size = TCPOLEN_MPTCP_DSS_ACK64;
+ opts->ext_copy.data_ack = ack_seq;
+ opts->ext_copy.ack64 = 1;
+ } else {
+ ack_size = TCPOLEN_MPTCP_DSS_ACK32;
+ opts->ext_copy.data_ack32 = (uint32_t)ack_seq;
+ opts->ext_copy.ack64 = 0;
+ }
+ opts->ext_copy.use_ack = 1;
+ opts->suboptions = OPTION_MPTCP_DSS;
+ WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk));
+
+ /* Add kind/length/subtype/flag overhead if mapping is not populated */
+ if (dss_size == 0)
+ ack_size += TCPOLEN_MPTCP_DSS_BASE;
+
+ dss_size += ack_size;
+
+ *size = ALIGN(dss_size, 4);
+ return true;
+}
+
+static u64 add_addr_generate_hmac(u64 key1, u64 key2,
+ struct mptcp_addr_info *addr)
+{
+ u16 port = ntohs(addr->port);
+ u8 hmac[SHA256_DIGEST_SIZE];
+ u8 msg[19];
+ int i = 0;
+
+ msg[i++] = addr->id;
+ if (addr->family == AF_INET) {
+ memcpy(&msg[i], &addr->addr.s_addr, 4);
+ i += 4;
+ }
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+ else if (addr->family == AF_INET6) {
+ memcpy(&msg[i], &addr->addr6.s6_addr, 16);
+ i += 16;
+ }
+#endif
+ msg[i++] = port >> 8;
+ msg[i++] = port & 0xFF;
+
+ mptcp_crypto_hmac_sha(key1, key2, msg, i, hmac);
+
+ return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
+}
+
+static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *skb,
+ unsigned int *size,
+ unsigned int remaining,
+ struct mptcp_out_options *opts)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+ bool drop_other_suboptions = false;
+ unsigned int opt_size = *size;
+ bool echo;
+ int len;
+
+ /* add addr will strip the existing options, be sure to avoid breaking
+ * MPC/MPJ handshakes
+ */
+ if (!mptcp_pm_should_add_signal(msk) ||
+ (opts->suboptions & (OPTION_MPTCP_MPJ_ACK | OPTION_MPTCP_MPC_ACK)) ||
+ !mptcp_pm_add_addr_signal(msk, skb, opt_size, remaining, &opts->addr,
+ &echo, &drop_other_suboptions))
+ return false;
+
+ if (drop_other_suboptions)
+ remaining += opt_size;
+ len = mptcp_add_addr_len(opts->addr.family, echo, !!opts->addr.port);
+ if (remaining < len)
+ return false;
+
+ *size = len;
+ if (drop_other_suboptions) {
+ pr_debug("drop other suboptions");
+ opts->suboptions = 0;
+
+ /* note that e.g. DSS could have written into the memory
+ * aliased by ahmac, we must reset the field here
+ * to avoid appending the hmac even for ADD_ADDR echo
+ * options
+ */
+ opts->ahmac = 0;
+ *size -= opt_size;
+ }
+ opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
+ if (!echo) {
+ opts->ahmac = add_addr_generate_hmac(msk->local_key,
+ msk->remote_key,
+ &opts->addr);
+ }
+ pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d",
+ opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port));
+
+ return true;
+}
+
+static bool mptcp_established_options_rm_addr(struct sock *sk,
+ unsigned int *size,
+ unsigned int remaining,
+ struct mptcp_out_options *opts)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+ struct mptcp_rm_list rm_list;
+ int i, len;
+
+ if (!mptcp_pm_should_rm_signal(msk) ||
+ !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_list)))
+ return false;
+
+ len = mptcp_rm_addr_len(&rm_list);
+ if (len < 0)
+ return false;
+ if (remaining < len)
+ return false;
+
+ *size = len;
+ opts->suboptions |= OPTION_MPTCP_RM_ADDR;
+ opts->rm_list = rm_list;
+
+ for (i = 0; i < opts->rm_list.nr; i++)
+ pr_debug("rm_list_ids[%d]=%d", i, opts->rm_list.ids[i]);
+
+ return true;
+}
+
+static bool mptcp_established_options_mp_prio(struct sock *sk,
+ unsigned int *size,
+ unsigned int remaining,
+ struct mptcp_out_options *opts)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+
+ /* can't send MP_PRIO with MPC, as they share the same option space:
+ * 'backup'. Also it makes no sense at all
+ */
+ if (!subflow->send_mp_prio || (opts->suboptions & OPTIONS_MPTCP_MPC))
+ return false;
+
+ /* account for the trailing 'nop' option */
+ if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN)
+ return false;
+
+ *size = TCPOLEN_MPTCP_PRIO_ALIGN;
+ opts->suboptions |= OPTION_MPTCP_PRIO;
+ opts->backup = subflow->request_bkup;
+
+ pr_debug("prio=%d", opts->backup);
+
+ return true;
+}
+
+static noinline bool mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb,
+ unsigned int *size,
+ unsigned int remaining,
+ struct mptcp_out_options *opts)
+{
+ const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+
+ if (remaining < TCPOLEN_MPTCP_RST)
+ return false;
+
+ *size = TCPOLEN_MPTCP_RST;
+ opts->suboptions |= OPTION_MPTCP_RST;
+ opts->reset_transient = subflow->reset_transient;
+ opts->reset_reason = subflow->reset_reason;
+ MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTTX);
+
+ return true;
+}
+
+static bool mptcp_established_options_fastclose(struct sock *sk,
+ unsigned int *size,
+ unsigned int remaining,
+ struct mptcp_out_options *opts)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+
+ if (likely(!subflow->send_fastclose))
+ return false;
+
+ if (remaining < TCPOLEN_MPTCP_FASTCLOSE)
+ return false;
+
+ *size = TCPOLEN_MPTCP_FASTCLOSE;
+ opts->suboptions |= OPTION_MPTCP_FASTCLOSE;
+ opts->rcvr_key = msk->remote_key;
+
+ pr_debug("FASTCLOSE key=%llu", opts->rcvr_key);
+ MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSETX);
+ return true;
+}
+
+static bool mptcp_established_options_mp_fail(struct sock *sk,
+ unsigned int *size,
+ unsigned int remaining,
+ struct mptcp_out_options *opts)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+
+ if (likely(!subflow->send_mp_fail))
+ return false;
+
+ if (remaining < TCPOLEN_MPTCP_FAIL)
+ return false;
+
+ *size = TCPOLEN_MPTCP_FAIL;
+ opts->suboptions |= OPTION_MPTCP_FAIL;
+ opts->fail_seq = subflow->map_seq;
+
+ pr_debug("MP_FAIL fail_seq=%llu", opts->fail_seq);
+ MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILTX);
+
+ return true;
+}
+
+bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
+ unsigned int *size, unsigned int remaining,
+ struct mptcp_out_options *opts)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+ unsigned int opt_size = 0;
+ bool snd_data_fin;
+ bool ret = false;
+
+ opts->suboptions = 0;
+
+ if (unlikely(__mptcp_check_fallback(msk) && !mptcp_check_infinite_map(skb)))
+ return false;
+
+ if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) {
+ if (mptcp_established_options_fastclose(sk, &opt_size, remaining, opts) ||
+ mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) {
+ *size += opt_size;
+ remaining -= opt_size;
+ }
+ /* MP_RST can be used with MP_FASTCLOSE and MP_FAIL if there is room */
+ if (mptcp_established_options_rst(sk, skb, &opt_size, remaining, opts)) {
+ *size += opt_size;
+ remaining -= opt_size;
+ }
+ return true;
+ }
+
+ snd_data_fin = mptcp_data_fin_enabled(msk);
+ if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, remaining, opts))
+ ret = true;
+ else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, remaining, opts)) {
+ unsigned int mp_fail_size;
+
+ ret = true;
+ if (mptcp_established_options_mp_fail(sk, &mp_fail_size,
+ remaining - opt_size, opts)) {
+ *size += opt_size + mp_fail_size;
+ remaining -= opt_size - mp_fail_size;
+ return true;
+ }
+ }
+
+ /* we reserved enough space for the above options, and exceeding the
+ * TCP option space would be fatal
+ */
+ if (WARN_ON_ONCE(opt_size > remaining))
+ return false;
+
+ *size += opt_size;
+ remaining -= opt_size;
+ if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) {
+ *size += opt_size;
+ remaining -= opt_size;
+ ret = true;
+ } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) {
+ *size += opt_size;
+ remaining -= opt_size;
+ ret = true;
+ }
+
+ if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) {
+ *size += opt_size;
+ remaining -= opt_size;
+ ret = true;
+ }
+
+ return ret;
+}
+
+bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
+ struct mptcp_out_options *opts)
+{
+ struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
+
+ if (subflow_req->mp_capable) {
+ opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
+ opts->sndr_key = subflow_req->local_key;
+ opts->csum_reqd = subflow_req->csum_reqd;
+ opts->allow_join_id0 = subflow_req->allow_join_id0;
+ *size = TCPOLEN_MPTCP_MPC_SYNACK;
+ pr_debug("subflow_req=%p, local_key=%llu",
+ subflow_req, subflow_req->local_key);
+ return true;
+ } else if (subflow_req->mp_join) {
+ opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
+ opts->backup = subflow_req->backup;
+ opts->join_id = subflow_req->local_id;
+ opts->thmac = subflow_req->thmac;
+ opts->nonce = subflow_req->local_nonce;
+ pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
+ subflow_req, opts->backup, opts->join_id,
+ opts->thmac, opts->nonce);
+ *size = TCPOLEN_MPTCP_MPJ_SYNACK;
+ return true;
+ }
+ return false;
+}
+
+static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
+ struct mptcp_subflow_context *subflow,
+ struct sk_buff *skb,
+ struct mptcp_options_received *mp_opt)
+{
+ /* here we can process OoO, in-window pkts, only in-sequence 4th ack
+ * will make the subflow fully established
+ */
+ if (likely(subflow->fully_established)) {
+ /* on passive sockets, check for 3rd ack retransmission
+ * note that msk is always set by subflow_syn_recv_sock()
+ * for mp_join subflows
+ */
+ if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&
+ TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&
+ subflow->mp_join && (mp_opt->suboptions & OPTIONS_MPTCP_MPJ) &&
+ !subflow->request_join)
+ tcp_send_ack(ssk);
+ goto fully_established;
+ }
+
+ /* we must process OoO packets before the first subflow is fully
+ * established. OoO packets are instead a protocol violation
+ * for MP_JOIN subflows as the peer must not send any data
+ * before receiving the forth ack - cfr. RFC 8684 section 3.2.
+ */
+ if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) {
+ if (subflow->mp_join)
+ goto reset;
+ return subflow->mp_capable;
+ }
+
+ if (((mp_opt->suboptions & OPTION_MPTCP_DSS) && mp_opt->use_ack) ||
+ ((mp_opt->suboptions & OPTION_MPTCP_ADD_ADDR) && !mp_opt->echo)) {
+ /* subflows are fully established as soon as we get any
+ * additional ack, including ADD_ADDR.
+ */
+ subflow->fully_established = 1;
+ WRITE_ONCE(msk->fully_established, true);
+ goto fully_established;
+ }
+
+ /* If the first established packet does not contain MP_CAPABLE + data
+ * then fallback to TCP. Fallback scenarios requires a reset for
+ * MP_JOIN subflows.
+ */
+ if (!(mp_opt->suboptions & OPTIONS_MPTCP_MPC)) {
+ if (subflow->mp_join)
+ goto reset;
+ subflow->mp_capable = 0;
+ pr_fallback(msk);
+ mptcp_do_fallback(ssk);
+ return false;
+ }
+
+ if (mp_opt->deny_join_id0)
+ WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
+
+ if (unlikely(!READ_ONCE(msk->pm.server_side)))
+ pr_warn_once("bogus mpc option on established client sk");
+ mptcp_subflow_fully_established(subflow, mp_opt);
+
+fully_established:
+ /* if the subflow is not already linked into the conn_list, we can't
+ * notify the PM: this subflow is still on the listener queue
+ * and the PM possibly acquiring the subflow lock could race with
+ * the listener close
+ */
+ if (likely(subflow->pm_notified) || list_empty(&subflow->node))
+ return true;
+
+ subflow->pm_notified = 1;
+ if (subflow->mp_join) {
+ clear_3rdack_retransmission(ssk);
+ mptcp_pm_subflow_established(msk);
+ } else {
+ mptcp_pm_fully_established(msk, ssk, GFP_ATOMIC);
+ }
+ return true;
+
+reset:
+ mptcp_subflow_reset(ssk);
+ return false;
+}
+
+u64 __mptcp_expand_seq(u64 old_seq, u64 cur_seq)
+{
+ u32 old_seq32, cur_seq32;
+
+ old_seq32 = (u32)old_seq;
+ cur_seq32 = (u32)cur_seq;
+ cur_seq = (old_seq & GENMASK_ULL(63, 32)) + cur_seq32;
+ if (unlikely(cur_seq32 < old_seq32 && before(old_seq32, cur_seq32)))
+ return cur_seq + (1LL << 32);
+
+ /* reverse wrap could happen, too */
+ if (unlikely(cur_seq32 > old_seq32 && after(old_seq32, cur_seq32)))
+ return cur_seq - (1LL << 32);
+ return cur_seq;
+}
+
+static void ack_update_msk(struct mptcp_sock *msk,
+ struct sock *ssk,
+ struct mptcp_options_received *mp_opt)
+{
+ u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt);
+ struct sock *sk = (struct sock *)msk;
+ u64 old_snd_una;
+
+ mptcp_data_lock(sk);
+
+ /* avoid ack expansion on update conflict, to reduce the risk of
+ * wrongly expanding to a future ack sequence number, which is way
+ * more dangerous than missing an ack
+ */
+ old_snd_una = msk->snd_una;
+ new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
+
+ /* ACK for data not even sent yet? Ignore.*/
+ if (unlikely(after64(new_snd_una, snd_nxt)))
+ new_snd_una = old_snd_una;
+
+ new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd;
+
+ if (after64(new_wnd_end, msk->wnd_end))
+ msk->wnd_end = new_wnd_end;
+
+ /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */
+ if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt)))
+ __mptcp_check_push(sk, ssk);
+
+ if (after64(new_snd_una, old_snd_una)) {
+ msk->snd_una = new_snd_una;
+ __mptcp_data_acked(sk);
+ }
+ mptcp_data_unlock(sk);
+
+ trace_ack_update_msk(mp_opt->data_ack,
+ old_snd_una, new_snd_una,
+ new_wnd_end, msk->wnd_end);
+}
+
+bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit)
+{
+ /* Skip if DATA_FIN was already received.
+ * If updating simultaneously with the recvmsg loop, values
+ * should match. If they mismatch, the peer is misbehaving and
+ * we will prefer the most recent information.
+ */
+ if (READ_ONCE(msk->rcv_data_fin))
+ return false;
+
+ WRITE_ONCE(msk->rcv_data_fin_seq,
+ mptcp_expand_seq(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit));
+ WRITE_ONCE(msk->rcv_data_fin, 1);
+
+ return true;
+}
+
+static bool add_addr_hmac_valid(struct mptcp_sock *msk,
+ struct mptcp_options_received *mp_opt)
+{
+ u64 hmac = 0;
+
+ if (mp_opt->echo)
+ return true;
+
+ hmac = add_addr_generate_hmac(msk->remote_key,
+ msk->local_key,
+ &mp_opt->addr);
+
+ pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
+ msk, hmac, mp_opt->ahmac);
+
+ return hmac == mp_opt->ahmac;
+}
+
+/* Return false if a subflow has been reset, else return true */
+bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+ struct mptcp_options_received mp_opt;
+ struct mptcp_ext *mpext;
+
+ if (__mptcp_check_fallback(msk)) {
+ /* Keep it simple and unconditionally trigger send data cleanup and
+ * pending queue spooling. We will need to acquire the data lock
+ * for more accurate checks, and once the lock is acquired, such
+ * helpers are cheap.
+ */
+ mptcp_data_lock(subflow->conn);
+ if (sk_stream_memory_free(sk))
+ __mptcp_check_push(subflow->conn, sk);
+ __mptcp_data_acked(subflow->conn);
+ mptcp_data_unlock(subflow->conn);
+ return true;
+ }
+
+ mptcp_get_options(skb, &mp_opt);
+
+ /* The subflow can be in close state only if check_fully_established()
+ * just sent a reset. If so, tell the caller to ignore the current packet.
+ */
+ if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
+ return sk->sk_state != TCP_CLOSE;
+
+ if (unlikely(mp_opt.suboptions != OPTION_MPTCP_DSS)) {
+ if ((mp_opt.suboptions & OPTION_MPTCP_FASTCLOSE) &&
+ msk->local_key == mp_opt.rcvr_key) {
+ WRITE_ONCE(msk->rcv_fastclose, true);
+ mptcp_schedule_work((struct sock *)msk);
+ MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSERX);
+ }
+
+ if ((mp_opt.suboptions & OPTION_MPTCP_ADD_ADDR) &&
+ add_addr_hmac_valid(msk, &mp_opt)) {
+ if (!mp_opt.echo) {
+ mptcp_pm_add_addr_received(sk, &mp_opt.addr);
+ MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
+ } else {
+ mptcp_pm_add_addr_echoed(msk, &mp_opt.addr);
+ mptcp_pm_del_add_timer(msk, &mp_opt.addr, true);
+ MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);
+ }
+
+ if (mp_opt.addr.port)
+ MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD);
+ }
+
+ if (mp_opt.suboptions & OPTION_MPTCP_RM_ADDR)
+ mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list);
+
+ if (mp_opt.suboptions & OPTION_MPTCP_PRIO) {
+ mptcp_pm_mp_prio_received(sk, mp_opt.backup);
+ MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX);
+ }
+
+ if (mp_opt.suboptions & OPTION_MPTCP_FAIL) {
+ mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq);
+ MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILRX);
+ }
+
+ if (mp_opt.suboptions & OPTION_MPTCP_RST) {
+ subflow->reset_seen = 1;
+ subflow->reset_reason = mp_opt.reset_reason;
+ subflow->reset_transient = mp_opt.reset_transient;
+ MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTRX);
+ }
+
+ if (!(mp_opt.suboptions & OPTION_MPTCP_DSS))
+ return true;
+ }
+
+ /* we can't wait for recvmsg() to update the ack_seq, otherwise
+ * monodirectional flows will stuck
+ */
+ if (mp_opt.use_ack)
+ ack_update_msk(msk, sk, &mp_opt);
+
+ /* Zero-data-length packets are dropped by the caller and not
+ * propagated to the MPTCP layer, so the skb extension does not
+ * need to be allocated or populated. DATA_FIN information, if
+ * present, needs to be updated here before the skb is freed.
+ */
+ if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
+ if (mp_opt.data_fin && mp_opt.data_len == 1 &&
+ mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64))
+ mptcp_schedule_work((struct sock *)msk);
+
+ return true;
+ }
+
+ mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
+ if (!mpext)
+ return true;
+
+ memset(mpext, 0, sizeof(*mpext));
+
+ if (likely(mp_opt.use_map)) {
+ if (mp_opt.mpc_map) {
+ /* this is an MP_CAPABLE carrying MPTCP data
+ * we know this map the first chunk of data
+ */
+ mptcp_crypto_key_sha(subflow->remote_key, NULL,
+ &mpext->data_seq);
+ mpext->data_seq++;
+ mpext->subflow_seq = 1;
+ mpext->dsn64 = 1;
+ mpext->mpc_map = 1;
+ mpext->data_fin = 0;
+ } else {
+ mpext->data_seq = mp_opt.data_seq;
+ mpext->subflow_seq = mp_opt.subflow_seq;
+ mpext->dsn64 = mp_opt.dsn64;
+ mpext->data_fin = mp_opt.data_fin;
+ }
+ mpext->data_len = mp_opt.data_len;
+ mpext->use_map = 1;
+ mpext->csum_reqd = !!(mp_opt.suboptions & OPTION_MPTCP_CSUMREQD);
+
+ if (mpext->csum_reqd)
+ mpext->csum = mp_opt.csum;
+ }
+
+ return true;
+}
+
+static void mptcp_set_rwin(struct tcp_sock *tp, struct tcphdr *th)
+{
+ const struct sock *ssk = (const struct sock *)tp;
+ struct mptcp_subflow_context *subflow;
+ u64 ack_seq, rcv_wnd_old, rcv_wnd_new;
+ struct mptcp_sock *msk;
+ u32 new_win;
+ u64 win;
+
+ subflow = mptcp_subflow_ctx(ssk);
+ msk = mptcp_sk(subflow->conn);
+
+ ack_seq = READ_ONCE(msk->ack_seq);
+ rcv_wnd_new = ack_seq + tp->rcv_wnd;
+
+ rcv_wnd_old = atomic64_read(&msk->rcv_wnd_sent);
+ if (after64(rcv_wnd_new, rcv_wnd_old)) {
+ u64 rcv_wnd;
+
+ for (;;) {
+ rcv_wnd = atomic64_cmpxchg(&msk->rcv_wnd_sent, rcv_wnd_old, rcv_wnd_new);
+
+ if (rcv_wnd == rcv_wnd_old)
+ break;
+
+ rcv_wnd_old = rcv_wnd;
+ if (before64(rcv_wnd_new, rcv_wnd_old)) {
+ MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICTUPDATE);
+ goto raise_win;
+ }
+ MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICT);
+ }
+ return;
+ }
+
+ if (rcv_wnd_new != rcv_wnd_old) {
+raise_win:
+ win = rcv_wnd_old - ack_seq;
+ tp->rcv_wnd = min_t(u64, win, U32_MAX);
+ new_win = tp->rcv_wnd;
+
+ /* Make sure we do not exceed the maximum possible
+ * scaled window.
+ */
+ if (unlikely(th->syn))
+ new_win = min(new_win, 65535U) << tp->rx_opt.rcv_wscale;
+ if (!tp->rx_opt.rcv_wscale &&
+ READ_ONCE(sock_net(ssk)->ipv4.sysctl_tcp_workaround_signed_windows))
+ new_win = min(new_win, MAX_TCP_WINDOW);
+ else
+ new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale));
+
+ /* RFC1323 scaling applied */
+ new_win >>= tp->rx_opt.rcv_wscale;
+ th->window = htons(new_win);
+ MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDSHARED);
+ }
+}
+
+__sum16 __mptcp_make_csum(u64 data_seq, u32 subflow_seq, u16 data_len, __wsum sum)
+{
+ struct csum_pseudo_header header;
+ __wsum csum;
+
+ /* cfr RFC 8684 3.3.1.:
+ * the data sequence number used in the pseudo-header is
+ * always the 64-bit value, irrespective of what length is used in the
+ * DSS option itself.
+ */
+ header.data_seq = cpu_to_be64(data_seq);
+ header.subflow_seq = htonl(subflow_seq);
+ header.data_len = htons(data_len);
+ header.csum = 0;
+
+ csum = csum_partial(&header, sizeof(header), sum);
+ return csum_fold(csum);
+}
+
+static __sum16 mptcp_make_csum(const struct mptcp_ext *mpext)
+{
+ return __mptcp_make_csum(mpext->data_seq, mpext->subflow_seq, mpext->data_len,
+ ~csum_unfold(mpext->csum));
+}
+
+static void put_len_csum(u16 len, __sum16 csum, void *data)
+{
+ __sum16 *sumptr = data + 2;
+ __be16 *ptr = data;
+
+ put_unaligned_be16(len, ptr);
+
+ put_unaligned(csum, sumptr);
+}
+
+void mptcp_write_options(struct tcphdr *th, __be32 *ptr, struct tcp_sock *tp,
+ struct mptcp_out_options *opts)
+{
+ const struct sock *ssk = (const struct sock *)tp;
+ struct mptcp_subflow_context *subflow;
+
+ /* Which options can be used together?
+ *
+ * X: mutually exclusive
+ * O: often used together
+ * C: can be used together in some cases
+ * P: could be used together but we prefer not to (optimisations)
+ *
+ * Opt: | MPC | MPJ | DSS | ADD | RM | PRIO | FAIL | FC |
+ * ------|------|------|------|------|------|------|------|------|
+ * MPC |------|------|------|------|------|------|------|------|
+ * MPJ | X |------|------|------|------|------|------|------|
+ * DSS | X | X |------|------|------|------|------|------|
+ * ADD | X | X | P |------|------|------|------|------|
+ * RM | C | C | C | P |------|------|------|------|
+ * PRIO | X | C | C | C | C |------|------|------|
+ * FAIL | X | X | C | X | X | X |------|------|
+ * FC | X | X | X | X | X | X | X |------|
+ * RST | X | X | X | X | X | X | O | O |
+ * ------|------|------|------|------|------|------|------|------|
+ *
+ * The same applies in mptcp_established_options() function.
+ */
+ if (likely(OPTION_MPTCP_DSS & opts->suboptions)) {
+ struct mptcp_ext *mpext = &opts->ext_copy;
+ u8 len = TCPOLEN_MPTCP_DSS_BASE;
+ u8 flags = 0;
+
+ if (mpext->use_ack) {
+ flags = MPTCP_DSS_HAS_ACK;
+ if (mpext->ack64) {
+ len += TCPOLEN_MPTCP_DSS_ACK64;
+ flags |= MPTCP_DSS_ACK64;
+ } else {
+ len += TCPOLEN_MPTCP_DSS_ACK32;
+ }
+ }
+
+ if (mpext->use_map) {
+ len += TCPOLEN_MPTCP_DSS_MAP64;
+
+ /* Use only 64-bit mapping flags for now, add
+ * support for optional 32-bit mappings later.
+ */
+ flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
+ if (mpext->data_fin)
+ flags |= MPTCP_DSS_DATA_FIN;
+
+ if (opts->csum_reqd)
+ len += TCPOLEN_MPTCP_DSS_CHECKSUM;
+ }
+
+ *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
+
+ if (mpext->use_ack) {
+ if (mpext->ack64) {
+ put_unaligned_be64(mpext->data_ack, ptr);
+ ptr += 2;
+ } else {
+ put_unaligned_be32(mpext->data_ack32, ptr);
+ ptr += 1;
+ }
+ }
+
+ if (mpext->use_map) {
+ put_unaligned_be64(mpext->data_seq, ptr);
+ ptr += 2;
+ put_unaligned_be32(mpext->subflow_seq, ptr);
+ ptr += 1;
+ if (opts->csum_reqd) {
+ /* data_len == 0 is reserved for the infinite mapping,
+ * the checksum will also be set to 0.
+ */
+ put_len_csum(mpext->data_len,
+ (mpext->data_len ? mptcp_make_csum(mpext) : 0),
+ ptr);
+ } else {
+ put_unaligned_be32(mpext->data_len << 16 |
+ TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
+ }
+ ptr += 1;
+ }
+
+ /* We might need to add MP_FAIL options in rare cases */
+ if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions))
+ goto mp_fail;
+ } else if (OPTIONS_MPTCP_MPC & opts->suboptions) {
+ u8 len, flag = MPTCP_CAP_HMAC_SHA256;
+
+ if (OPTION_MPTCP_MPC_SYN & opts->suboptions) {
+ len = TCPOLEN_MPTCP_MPC_SYN;
+ } else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) {
+ len = TCPOLEN_MPTCP_MPC_SYNACK;
+ } else if (opts->data_len) {
+ len = TCPOLEN_MPTCP_MPC_ACK_DATA;
+ if (opts->csum_reqd)
+ len += TCPOLEN_MPTCP_DSS_CHECKSUM;
+ } else {
+ len = TCPOLEN_MPTCP_MPC_ACK;
+ }
+
+ if (opts->csum_reqd)
+ flag |= MPTCP_CAP_CHECKSUM_REQD;
+
+ if (!opts->allow_join_id0)
+ flag |= MPTCP_CAP_DENY_JOIN_ID0;
+
+ *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
+ MPTCP_SUPPORTED_VERSION,
+ flag);
+
+ if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
+ opts->suboptions))
+ goto mp_capable_done;
+
+ put_unaligned_be64(opts->sndr_key, ptr);
+ ptr += 2;
+ if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions))
+ goto mp_capable_done;
+
+ put_unaligned_be64(opts->rcvr_key, ptr);
+ ptr += 2;
+ if (!opts->data_len)
+ goto mp_capable_done;
+
+ if (opts->csum_reqd) {
+ put_len_csum(opts->data_len,
+ __mptcp_make_csum(opts->data_seq,
+ opts->subflow_seq,
+ opts->data_len,
+ ~csum_unfold(opts->csum)),
+ ptr);
+ } else {
+ put_unaligned_be32(opts->data_len << 16 |
+ TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
+ }
+ ptr += 1;
+
+ /* MPC is additionally mutually exclusive with MP_PRIO */
+ goto mp_capable_done;
+ } else if (OPTIONS_MPTCP_MPJ & opts->suboptions) {
+ if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
+ *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
+ TCPOLEN_MPTCP_MPJ_SYN,
+ opts->backup, opts->join_id);
+ put_unaligned_be32(opts->token, ptr);
+ ptr += 1;
+ put_unaligned_be32(opts->nonce, ptr);
+ ptr += 1;
+ } else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
+ *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
+ TCPOLEN_MPTCP_MPJ_SYNACK,
+ opts->backup, opts->join_id);
+ put_unaligned_be64(opts->thmac, ptr);
+ ptr += 2;
+ put_unaligned_be32(opts->nonce, ptr);
+ ptr += 1;
+ } else {
+ *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
+ TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
+ memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
+ ptr += 5;
+ }
+ } else if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
+ u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
+ u8 echo = MPTCP_ADDR_ECHO;
+
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+ if (opts->addr.family == AF_INET6)
+ len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
+#endif
+
+ if (opts->addr.port)
+ len += TCPOLEN_MPTCP_PORT_LEN;
+
+ if (opts->ahmac) {
+ len += sizeof(opts->ahmac);
+ echo = 0;
+ }
+
+ *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
+ len, echo, opts->addr.id);
+ if (opts->addr.family == AF_INET) {
+ memcpy((u8 *)ptr, (u8 *)&opts->addr.addr.s_addr, 4);
+ ptr += 1;
+ }
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+ else if (opts->addr.family == AF_INET6) {
+ memcpy((u8 *)ptr, opts->addr.addr6.s6_addr, 16);
+ ptr += 4;
+ }
+#endif
+
+ if (!opts->addr.port) {
+ if (opts->ahmac) {
+ put_unaligned_be64(opts->ahmac, ptr);
+ ptr += 2;
+ }
+ } else {
+ u16 port = ntohs(opts->addr.port);
+
+ if (opts->ahmac) {
+ u8 *bptr = (u8 *)ptr;
+
+ put_unaligned_be16(port, bptr);
+ bptr += 2;
+ put_unaligned_be64(opts->ahmac, bptr);
+ bptr += 8;
+ put_unaligned_be16(TCPOPT_NOP << 8 |
+ TCPOPT_NOP, bptr);
+
+ ptr += 3;
+ } else {
+ put_unaligned_be32(port << 16 |
+ TCPOPT_NOP << 8 |
+ TCPOPT_NOP, ptr);
+ ptr += 1;
+ }
+ }
+ } else if (unlikely(OPTION_MPTCP_FASTCLOSE & opts->suboptions)) {
+ /* FASTCLOSE is mutually exclusive with others except RST */
+ *ptr++ = mptcp_option(MPTCPOPT_MP_FASTCLOSE,
+ TCPOLEN_MPTCP_FASTCLOSE,
+ 0, 0);
+ put_unaligned_be64(opts->rcvr_key, ptr);
+ ptr += 2;
+
+ if (OPTION_MPTCP_RST & opts->suboptions)
+ goto mp_rst;
+ return;
+ } else if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) {
+mp_fail:
+ /* MP_FAIL is mutually exclusive with others except RST */
+ subflow = mptcp_subflow_ctx(ssk);
+ subflow->send_mp_fail = 0;
+
+ *ptr++ = mptcp_option(MPTCPOPT_MP_FAIL,
+ TCPOLEN_MPTCP_FAIL,
+ 0, 0);
+ put_unaligned_be64(opts->fail_seq, ptr);
+ ptr += 2;
+
+ if (OPTION_MPTCP_RST & opts->suboptions)
+ goto mp_rst;
+ return;
+ } else if (unlikely(OPTION_MPTCP_RST & opts->suboptions)) {
+mp_rst:
+ *ptr++ = mptcp_option(MPTCPOPT_RST,
+ TCPOLEN_MPTCP_RST,
+ opts->reset_transient,
+ opts->reset_reason);
+ return;
+ }
+
+ if (OPTION_MPTCP_PRIO & opts->suboptions) {
+ subflow = mptcp_subflow_ctx(ssk);
+ subflow->send_mp_prio = 0;
+
+ *ptr++ = mptcp_option(MPTCPOPT_MP_PRIO,
+ TCPOLEN_MPTCP_PRIO,
+ opts->backup, TCPOPT_NOP);
+
+ MPTCP_INC_STATS(sock_net((const struct sock *)tp),
+ MPTCP_MIB_MPPRIOTX);
+ }
+
+mp_capable_done:
+ if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
+ u8 i = 1;
+
+ *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR,
+ TCPOLEN_MPTCP_RM_ADDR_BASE + opts->rm_list.nr,
+ 0, opts->rm_list.ids[0]);
+
+ while (i < opts->rm_list.nr) {
+ u8 id1, id2, id3, id4;
+
+ id1 = opts->rm_list.ids[i];
+ id2 = i + 1 < opts->rm_list.nr ? opts->rm_list.ids[i + 1] : TCPOPT_NOP;
+ id3 = i + 2 < opts->rm_list.nr ? opts->rm_list.ids[i + 2] : TCPOPT_NOP;
+ id4 = i + 3 < opts->rm_list.nr ? opts->rm_list.ids[i + 3] : TCPOPT_NOP;
+ put_unaligned_be32(id1 << 24 | id2 << 16 | id3 << 8 | id4, ptr);
+ ptr += 1;
+ i += 4;
+ }
+ }
+
+ if (tp)
+ mptcp_set_rwin(tp, th);
+}
+
+__be32 mptcp_get_reset_option(const struct sk_buff *skb)
+{
+ const struct mptcp_ext *ext = mptcp_get_ext(skb);
+ u8 flags, reason;
+
+ if (ext) {
+ flags = ext->reset_transient;
+ reason = ext->reset_reason;
+
+ return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST,
+ flags, reason);
+ }
+
+ return htonl(0u);
+}
+EXPORT_SYMBOL_GPL(mptcp_get_reset_option);